[LTP] [PATCH v1 3/3] memcontrol05: copy from kernel selftest test_cgcore_lesser_euid_open

[Yang Xu]

Signed-off-by: Yang Xu <xuyang2018.jy@fujitsu.com>
---
TODO: In the future, also add a regression test in cgroup namespace[1]
if I have free time. Or, I will add it on v2.
[1]https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=bf35a787
 runtest/controllers                           |  1 +
 testcases/kernel/controllers/memcg/.gitignore |  1 +
 .../kernel/controllers/memcg/memcontrol05.c   | 90 +++++++++++++++++++
 3 files changed, 92 insertions(+)
 create mode 100644 testcases/kernel/controllers/memcg/memcontrol05.c

diff --git a/runtest/controllers b/runtest/controllers
index 22d482050..5c51a414a 100644
--- a/runtest/controllers
+++ b/runtest/controllers
@@ -21,6 +21,7 @@ memcontrol01 memcontrol01
 memcontrol02 memcontrol02
 memcontrol03 memcontrol03
 memcontrol04 memcontrol04
+memcontrol05 memcontrol05
 
 cgroup_fj_function_debug cgroup_fj_function.sh debug
 cgroup_fj_function_cpuset cgroup_fj_function.sh cpuset
diff --git a/testcases/kernel/controllers/memcg/.gitignore b/testcases/kernel/controllers/memcg/.gitignore
index 3883cede6..8b9f6005c 100644
--- a/testcases/kernel/controllers/memcg/.gitignore
+++ b/testcases/kernel/controllers/memcg/.gitignore
@@ -9,3 +9,4 @@ memcontrol01
 memcontrol02
 memcontrol03
 memcontrol04
+memcontrol05
diff --git a/testcases/kernel/controllers/memcg/memcontrol05.c b/testcases/kernel/controllers/memcg/memcontrol05.c
new file mode 100644
index 000000000..24976b602
--- /dev/null
+++ b/testcases/kernel/controllers/memcg/memcontrol05.c
@@ -0,0 +1,90 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2022 FUJITSU LIMITED. All rights reserved.
+ * Author: Yang Xu <xuyang2018.jy@cn.fujitsu.com>
+ */
+
+/*\
+ * [Description]
+ *
+ * When a task is writing to an fd opened by a different task, the perm check
+ * should use the credentials of the latter task.
+ *
+ * It is copy from kernel selftests cgroup test_core test_cgcore_lesser_euid_open
+ * subcase. The difference is that kernel selftest only supports cgroup v2 but
+ * here we also support cgroup v1 and v2.
+ *
+ * It is a regression test for
+ *
+ * commit e57457641613fef0d147ede8bd6a3047df588b95
+ * Author: Tejun Heo <tj@kernel.org>
+ * Date:   Thu Jan 6 11:02:29 2022 -1000
+ *
+ * cgroup: Use open-time cgroup namespace for process migration perm checks
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <sys/types.h>
+#include <pwd.h>
+#include "tst_test.h"
+#include "tst_safe_file_at.h"
+
+static struct tst_cg_group *cg_child;
+static uid_t nobody_uid, save_uid;
+
+static void test_lesser_euid_open(void)
+{
+	int fd;
+
+	cg_child = tst_cg_group_mk(tst_cg, "child");
+	if (!SAFE_FORK()) {
+		SAFE_CG_FCHOWN(cg_child, "cgroup.procs", nobody_uid, -1);
+		SAFE_SETEUID(nobody_uid);
+
+		fd = SAFE_CG_OPEN(cg_child, "cgroup.procs", O_RDWR);
+		SAFE_SETEUID(save_uid);
+
+		TEST(write(fd, "0", 1));
+		if (TST_RET >= 0 || TST_ERR != EACCES)
+			tst_res(TFAIL, "lesser_euid_open failed");
+		else
+			tst_res(TPASS | TTERRNO, "less_euid_open passed");
+
+		SAFE_CLOSE(fd);
+		exit(0);
+	}
+
+	tst_reap_children();
+	cg_child = tst_cg_group_rm(cg_child);
+}
+
+static void setup(void)
+{
+	struct passwd *pw;
+
+	pw = SAFE_GETPWNAM("nobody");
+	nobody_uid = pw->pw_uid;
+	save_uid = geteuid();
+}
+
+static void cleanup(void)
+{
+	if (cg_child) {
+		SAFE_CG_PRINTF(tst_cg_drain, "cgroup.procs", "%d", getpid());
+		cg_child = tst_cg_group_rm(cg_child);
+	}
+}
+
+static struct tst_test test = {
+	.setup = setup,
+	.cleanup = cleanup,
+	.test_all = test_lesser_euid_open,
+	.forks_child = 1,
+	.needs_root = 1,
+	.needs_cgroup_ctrls = (const char *const[]){ "memory", NULL },
+	.tags = (const struct tst_tag[]) {
+		{"linux-git", "e57457641613"},
+		{}
+	},
+};
-- 
2.27.0